C14 MgZn2-type CIF for MnFeSi inverted ordering (Fe at 2a(0,0,0), Mn at 2a(0,0,1/2)) — SG 194 P6_3/mmc. Fixed symmetry operations (ASE-compatible, no leading indices). Placeholder lattice a=5.00A, c=8.10A. Tests whether Fe/Mn site swap is energetically preferred vs MnFeSi_layered.